The effects of a liquid nutritive and tonic
drug (NTD) on the neurochemical changes elicited by physical
fatigue in mice were investigated in terms of the
calcium-dependent
dopamine synthesizing function of the brain. In this study,
Zena F-III (Taisho
Pharmaceutical Co., Ltd., Japan), one of the most popular NTDs in Japan, containing 15 crude
drug extracts together with
taurine,
caffeine, and
vitamins, and formulated based on the precepts of
traditional Chinese medicine, was used. Male mice were forced to walk for 0-6 h at a speed of 3 m/min using a programmed motor-driven wheel cage. The serum and brain
calcium levels in the mice were significantly increased following forced walking. The increase in brain
calcium level began later and was more gradual than that in the serum
calcium level, and reached its maximum value following forced walking for 3 h. The neostriatal
dopamine level was also significantly increased, and locomotor activity significantly decreased following forced walking for 3 h. Prior
oral administration of F-III (10 ml/kg) attenuated the increases in the serum and brain
calcium levels, the increase in the brain
dopamine levels, and the decrease in locomotor activity induced by forced walking. Taking into consideration these findings with our previous reports, it is suggested that physical
fatigue leads to an increase in
dopamine synthesis in the brain through a
calcium/
calmodulin-dependent system, thereby inducing behavioral changes, and that F-III inhibits this pathway and may alleviate overwork-induced physical
fatigue.